Tank sealant mistake, '94 VFR750F

I made a "slight tactical error" when sealing my '94 VFR fuel tank . There were some small surface rust patches beginning in the bottom, so i decided to etch and seal the tank with POR15 before the rust became an issue. I knew that I needed to blow though the internal tank vent before allowing the sealant to set up, but something distracted me from that little mission (Squirrel!) and I didn't discover the error until I put fuel in 4 days later.
I managed to find and clear one vent hole on the bottom of the vent assembly, within reach of the fuel gauge/low fuel sensor hole, but there has to be at least one more elsewhere out of sight.
Has anyone else ever had to fix the same dumb mistake? The only reasons a person would have knowledge of the location of the vent holes would be because they had to solve the same problem, or they were involved in assembling these tanks at the factory.
I have considered injecting some of POR-15's stripper product into the vent, but that would get the product onto surfaces inside of the tank that I don't want stripped. I have also considered pressurizing the vent assembly hoping that the blockage will pop off, but I have seen what air pressure can do to an object that is not meant to hold pressure! If that little experiment failed, I would have to hurt myself.
This bike is so clean that I think I would have a hard time finding a replacement tank that would stand out as different, and I have seen new parts that aren't quite the same paint batch.
I need to either get advice from someone who has solved the same problem, or find a destroyed fuel tank to cut open and look at the vent so I can come up with a smart plan of attack.
Any ideas out there?

 

Run a stiff wire through the vent hole and see where it comes out?

 

Won't work. The vent assembly is built like "a doughnut on a stick". The "doughnut" ring is at the top of the tank surrounding the filler. It is completely out of reach. The ring is hollow, and has breather holes in it, definitely on the bottom where I can see, and I have to assume on the top where I can't see. The ring allows air in and out of the tank through a tube that goes from the bottom rear of the ring, down through the bottom of the tank. I have cleared one hole on the bottom. This is allowing air into the tank as the fuel runs out to the carbs. But if i fill the tank up and the tank pressurizes at all, it forces fuel up into the vent, and out through the tube and vent hose to the ground. A real drag when your garage reeks of leaked gasoline.
If I can clear any other holes, especially on top, it makes sense to me that fuel could no longer be forced up into the vent.
If it was just the tube that was blocked, a bit of wire forced through would do the job. but the wire would have to be pretty smart to get into that ring, find a hole around the corner, change directions and poke through. (unless the hole is directly above the position where the tube is welded into the ring, but I doubt that because any fuel that splashed onto a hole there would just drip right down to that tube onto the ground.)
Am I making sense or mumbo-jumbo?
At this moment there is Por-15 stripper injected down the vent tube of my upside down tank, soaking in there. I don't know what else to do.
The moral of his story is simple. the POR15 product is awesome. Just be sure you clear anything that isn't supposed to be sealed BEFORE it sets up.
Here endeth the lesson.

 

YOU seem very knowledgable about our bikes, but doesn't the tank vent through a valve on the fuel filler cap ??

IF so, that makes the under-tank hole the drain from the filler cap pocket........ rain water or fuel overflow.

 

On my 94 there are two tubes that come out of the bottom of the tank. One is the internal vent, and the other is the overflow. The cap does not vent. I don't recall what my '90 had....
I've had to do some serious head scratching on this one!